Compass/motor calibration problem

Continuing the discussion from DEV: The biggest problem of Ardupilot - Compass Issues:

Hello there sir,
I have this issue that after crashing my apm 450 drone build my motor calibration is constantly failing. Also it is not indicate that my GPS compass is mounted though to the hardware are completely set. Can be the crash is responsible for this problem? And how can I fix it?.. Hopefully someone will read this messageā€¦:pray:

It seems like you might have connector problems. Also maybe a motor or ESC got damaged in the crash.
More detailed information would be needed.